There has been a longstanding need for adequate fire protection for essential electronic equipment to ensure its continuous operation and survivability under fire conditions. One approach has been to employ Halon gas as the sole fire fighting system for rooms filled with electronic equipment, particularly in those applications where it is necessary to avoid equipment damage by water or other types of fire estinguishing agents. However, reliance on a single fire fighting system could reduce the fire control capability and decrease the equipment survivability as compared to a facility equipped with multiple fire fighting systems. Also, Halon will only be effective when proper Halon volume concentration is maintained in the room. If the doors or windows of a room cannot be properly closed, or the ventilation to the room is not stopped, Halon's fire extinguishing ability will be diminished or totally ineffective. Other well known forms of fire fighting systems include equipment for directing gases, liquids, water or other fire extinguishing chemicals onto the fire. One example of such fire fighting systems is disclosed by Terry in U.S. Pat. No. 3,403,733 wherein a carbon dioxide fire extinguisher is used to extinguish a fire occuring within an electronic cabinet. The system disclosed by Terry is designed to extinguish fires occuring within a cabinet and, therefore, cannot protect the said equipment from an external fire originated in the room.
Several passive types of methods have been employed for the purpose of protecting electronic equipment during a fire and/or in fire fighting situations. For example, U.S. Pat. No. 4,135,055 to Beckers et al discloses a fireproofing casing having non-combustible, fire-resistant wall panels and means for closing the casing off so that fire gases cannot reach the protected electrical conductors contained therein. Similarly, U.S. Patent No. 4,413,683 to Hune discloses a fireproof enclosure made of flame proof refractory material that substantially encloses a valve actuator unit and prevents a flame path into the enclosure. The U.S. Pat. No. 3,119,452 to Sammis discloses a cooling device for a flight recorder wherein a coolant medium is contained with the recorder in an insulated housing and the coolant vaporizes under a predetermined temperature so as to absorb surrounding heat to maintain the recorder at a desired temperature. The internal cooling technique and the fire insulation method is designed to maintain small equipment, such as the flight recorder, intact during fire conditions. However, such cooling and insulating techniques are not practical, and sometimes are not possible due to space problems where a large array of control equipment must be protected from fire situations. Basically, they are not designed for the electronic equipment requirements, such as space problems and equipment survivability. Thus, the passive forms of fire protection for equipment are limited in space and their application, the extent and duration of the fire during which time the protection means must counter the effects of fire and heat, and their dependence upon the active fire extinguishing means being effective to bring about stoppage of the heat and fire condition in a short period of time.
In view of the above, it is an object of the present invention to maintain electronic equipment continuously functioning during an external fire and/or in a fire fighting situation. It is another object of the present invention to protect electronic equipment from fire damage and maintain its operation during fire situations occurruing over an extended length of time. It is another object to provide a fire resistant and spray proof cabinet system for electronic equipment of various sizes, without creating space problems due to the fire protection system. It is a further object to provide a fireproof cabinet system which is advantageous from the standpoint of equipment space and facility operation.